iMac 21.5" A1311 EMC2428 - No backlight

[HTR-Informatique]

Hello,
I have an iMac 21.5 "A1311 EMC 2428 from 2011.
I already changed the hard drive on it.
I have a backlight problem, I have a dark display on the internal screen, on an external screen no worries.
Before I had the screen blinking, the brightness only varied.
I bought a new backlight power supply (inverter) and now I have no backlight at all.
When I measure the input current of the card / output of the power supply for the inverter, I have nothing.
The power works well, but does not give any power to the inverter it seems.
By the way I had returned the card and bought another but the same.
I measured the current without the screen plugged in, but anyway I guess the power supply delivers the connected screen current or not.
Thank you in advance.

 

[2informaticos]

First of all, try another screen.
Which is the 820-xxxx code of your board?
Do you get image, only missing backlight?

 

[HTR-Informatique]

I had already tried with another screen at the very beginning of the same problem issues.
The screen is normally good.
Yes I have a display but dark.
820-2784

 

[2informaticos]

Do you get LCD_BKL_ON?
If not, post U9000 voltages.
Also check LCD_PWM.

 

[HTR-Informatique]

Deceived thread. Disregard this message.